This relates generally to imaging devices, and more particularly, to CMOS image sensors.
Modern electronic devices such cellular telephones, cameras, and computers often use digital image sensors. Imagers (i.e. image sensors) may be formed from a two-dimensional array of image sensing pixels. Each pixel may include a photosensor such as a photodiode that receives incident photons (light) and converts the photons into electrical signals. Image sensors are sometimes designed to provide images to electronic devices using a Joint Photographic Experts Group (JPEG) format or any other suitable image format.
As image sensor pixels become smaller in size and as image resolution increases, image sensor data rates continue to increase as a result. To meet performance requirements at high data rates, a column parallel architecture in which each pixel column is coupled to a respective analog-to-digital converter (ADC) has been developed. Typically, each column ADC is required to exhibit high resolution such as 12-bit resolution. High dynamic range (HDR) image sensors may require even more ADC resolution. Such types of high resolution ADCs can consume a significant amount of power, occupy a large percentage of die area, and require long conversion times.
It would therefore be desirable to be able to provide improved imaging devices for capturing high resolution images.